Concern over ozone depletion in the atmosphere has prompted calls for the replacement of chlorofluorocarbon foam blowing agents with blowing agents offering substantially reduced ozone depletion potential such as hydrocarbons.
Hydrocarbons and some other alternative blowing agents present their own unique problems. Chief among these is greater fire hazard in closed-cell foams due to entrapped blowing agent. Other problems however, may include toxicity or environmental incompatibility. The flame retardancy or environmental incompatibility of closed-cell foams may be slow to recover due to the relatively slow permeation of some blowing agents, including hydrocarbons, from the foams.
To address the problem of flame retardancy, it would be desirable to have a closed-cell foam structure which more quickly releases blowing agents, particularly flammable blowing agents. Also desirable would be a process for making such a foam structure.